1. Technical Field
This application generally relates to data storage systems, and more particularly to techniques used with controlling the performance of the data storage systems in accordance with performance goals.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more servers or host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and the storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data in the device. In order to facilitate sharing of the data on the device, additional software on the data storage systems may also be used.
Data storage systems and servers may be configured in a network arrangement referred to as a Storage Area Network (SAN). Each of the servers may have access to different physical devices, and/or logical portions thereof, included in the SAN. The data storage systems may process different types of requests from one or more applications executing on each of the servers or hosts connected to the data storage systems. It may be advantageous to process requests in a manner to achieve a desired performance goal. One technique may include controlling the I/O requests at the host side. However, this may require additional software being installed on each host. Another technique may include directly programming the data storage systems to process a certain number of requests of a particular type. If a performance goal is not met, the data storage system may be reprogrammed with revised numbers of the types of requests to process. The latter technique can be very time consuming and does not allow for changing environments and uses of the data storage systems.